Simultaneous alkylation and desulfurization



other hydrocarbons containing oleflns.

Patented Jan. 13, 1948.

SMULTAN'EOUS ALKYLATION AND DESULFURIZATION Jacob R. Meadow and William A. Stover, Woodbury, N.

J., aasignors to Socony-Vacunm Oil Company, Incorporated, a corporation of. New

York

No Drawing, Application June 29, 1944,

Serial No. 542,817

12 Claims. (CL 196-50) The present invention relates to the simultaneous alkylation and desulfurization of gas oil fractions of hydrocarbon oils by means of liquid hydrogen fluoride.

The alkylation of isoparafflns with oleflns in the presence of catalysts, such as sulfuric acid has been practiced by the art. However, in such alkyiationspractically pure materials are employed and alkylation of the paraflin is the sole object of the operation. In these prior art processes involving alkylation and employing substantially pure materials no attempt is made to desulfurize the materials employed and in fact no desulfurization is needed. On the other hand, it now has been discovered that complex mixtures of hydrocarbons, such as gas oil fractions of petroleum oil, can be alkylated employing complex mixtures of Furthermore, the materials employed are not restricted to materials of low sulfur content such as are presently used but may include materials of relatively high sulfur content. The use of such materials as those having a relatively high sulfur content is possible because the present invention provides a means for desulfurizing the materials substantially simultaneously with the alkylation reaction. Several advantages are obtained by the substantially simultaneous alkylation and desulfurization provided by the present process. Among these advantages are the use of high sulfur raw materials for the production of motor fuel of relatively low sulfur content, the use of mixtures of isoparafiins and other hydrocarbons as the stock to be alkylated in place of material which is substantially all isoparafiinic, the use of a mixture of olefins and other hydrocarbons as the alkylating material in place of material which is substantially solely oleflnic in nature, an increased yield of material boiling within the gasoline range, an increase in, the gasoline to coke ratio and a decrease in the amount of cycle stock.

While the present invention will be described in conjunction with the use of gas oil fractions having arelatively high sulfur content and the use of a naphtha of relatively high sulfur content, those skilled in the art will understand that variations in the sulfur content of the reacting materials above and below the sulfur content set forth hereinafter do not materially affect the broad advantages pointed out hereinbefore.

In general, the present process involves mixing a liquid fraction of hydrocarbon oil'containing alkylatable constituents, such as aromatics, with a liqud fraction of hydrocarbon oil containing alkylating compounds, such as oleflns, in the presence of liquid hydrogen fluoride. One of the aforesaid hydrocarbon fractions employed in the present process is a fraction suitable for cracking. In other words, a gas oil fraction containing alkylatable material and substantially devoid of alkylating material may be mixed with a naphtha containing alkylating substances. On the other hand, a cracking stock containing a suitable amount of alkylating material may be treated with a straight-run gasoline containing an appreciable amount of alkylatable material. Furthermore, both hydrocarbon fractions may contain both alkylatable and alkylating constituents. That is to say, the mixture of hydrocarbon fractions should contain at least 1 per cent by volume of alkylating substances and an amount of alkylatable material suflicient to alkylate with the total amount of alkylating material present in the mixture. Preferably, the olefin content of the alkylating fraction should be about 5 per cent to about 75 per cent, or such that the resulting mixture should not exceed 20 per cent by volume but preferably more than 1 per cent by volume of olefinic hydrocarbons. The alkylatable fraction may contain about 1 per cent to about 50 per cent of aromatics, or an amount sufficient to alkylate with the total olefins present in the mixture. The presence of a small amount of aromatics, say about 1 per cent to about-25 per cent in the alkylating fraction is not undesirable. Isoparaffinic hydrocarbons whose presence in the alkylating mixture is highly desirable may also be present. The amount of hydrogen fluoride is not sharply critical but should be sumcient to permit stratiflcation and formation of two separate layers. It has been found that the use of about 15 to about 100 pounds of hydrogen fluoride per 42 gallon barrel of alkylated fraction provides satisfactory results. Stated in other terms, about .051 pound to about 0.34 pound of hydrogen fluoride per pound of material (of density 0.85) treated will provide satisfactory results. It is to be understood, however, that the chief disadvantage in using more hydrogen fluoride, e. g., up to a pound of hydrogen fluoride to a pound of oil, is .the additional volume of hydrogen fluoride to be recovered.

A pressure of about 15 to about 40,pounds per square inch is sufllcient to maintain a major portion of the hydrogen fluoride in the liquid state at V a temperature of about 25 C. to about 40 C.

The mixture of hydrocarbons and liquid hydrogen fluoride is stirred for a period of time say about to about 30 minutes. After this period of treatment the reaction mixtureis allowed to stratify and the liquid hydrogen fluoride layer separated from the liquid hydrocarbon layer.

The hydrocarbon layer. is then subjected to cracking preferably in the presence of a catalyst. It is preferred to employ a silica-alumina catalyst for this purpose.

For the purposes ofillustrating the results obtained employing conditions within the ranges set forth hereinbefore, the following examples are provided for the guidance of those skilled in the art.

Example I A relatively high sulfur Texas gas oil was employed as the alkylatable fraction. This material had the following characteristics:

A. P. I. gravity 31.9 Initial boiling point, F 358 Sulfur content, weight per cent 1.57 Norwood bromine number 8.9 Aromatics volume per cent 34.2 Olefin content volume per cent A relatively high sulfur naphtha of the Visbreaker type and having the following characteristics was employed as the alkylating fraction:

A P. I. gravity 59.7 Initial boiling point, "F 112 Sulfur content, weight per cent 0.76

Norwood bromine number 89.2

Aromatics volume per cent 4.3 Olefin content volume per cent 64.3

The alkylatable fraction was mixed with the alkylating fraction in the ratio of about 436 parts by weight of the former to about 152 parts by weight of the latter. This mixture of gas oil plus Vis-breaker naphtha has a total olefinic content of about 18 to about 20 per cent by volume. To this mixture about 105 parts by weight of liquid hydrogen fluoride was added. Those skilled in the art will recognize that the hydrogen fluoride was employed in the ratio of about 5.6 parts by weight of oil to about 1 part by weight of hydrogen fluoride. The oil-hydrogen fluoride mixture was stirred in a closed container for about 20 to about 30 minutes at a temperature of about 25 C. to about 30 C. under the small amount of pressure, about 15 to about 20 pounds per square inch due to the vaporized hydrogen fluoride.

The contents of the container were allowed to stratify and the bottom layer of liquid hydrogen fluoride withdrawn. The raflinate, or treated oil substantially insoluble in hydrogen fluoride at 20 C. to 30 C. was then withdrawn and subjected to conventional catalytic cracking employing a silica-alumina catalyst, a temperature of about 800 F., a space velocity of 1.5, a pressure of about 10 pounds per square inch and a time "on stream of about 10 minutes.

The unstabilized gasoline fraction represented about 55.1 per cent of the charge to the case and the cycle stock about 36.9 per cent of the charge to the case. (Both values on a weight basis.) The untreated gas oil fraction on cracking yields about 43.7 per cent by weight unstabilized gasoline and about 46.4 per cent by weight of cycle stock. In the cracking of the alkylated gas 011 about 2.8 per cent of coke was produced whereas the cracking of the untreated gas oil resulted in the production of 3.7 per cent coke. The over-all yield of stabilized gasoline end point 410 F. from the alkylated fraction was about 56 per cent by weight based upon the amount of gas oil treated.

The advantages of the application of the principles of the present'invention can be readily appreciated by consideration of the following illustrative data.

A portion of the same gas oil as was used in Example I was employed as the alkylatable fraction and a portion of the same Vis-breaker naphtha as was used in Example I was employed as the alkylating fraction. These hydrocarbon fractions were mixed in the proportion of about 436 parts by weight (500 parts by volume) of gas oil to about 57 parts by weight (80 parts by volume) of naphtha. This mixture contains about 8 to about 10 per cent by volume total oleflns.

To the above mixture about 105 parts by weight of liquid hydrogen fluoride was added. Those skilled in the art will understand that the hydrogen fluoride was employed in the ratio of about 4.9 parts by weight of oil to about 1 part by weight of hydrogen fluoride. The oil-hydrogen fluoride mixture was stirred in a closed container for about 15 minutes at about 25 C. to about 30 C. and under a slight pressure of about 10 to about 20 pounds per square inch due to the vaporized hydrogen fluoride. The bottom layer of hydrogen fluoride and dissolved extract was withdrawn after allowing to settle. The ramnate, or treated oil substantially insoluble in hydrogen fluoride at about 20 C. to about 30 C., was then withdrawn and subjected to conventional catalytic cracking employing a silica-alumina catalyst, a temperature of about 800 F., a space velocity of 1.5, a v

pressureof about 10 pounds per square inch and a time On stream of about 10 minutes.

The unstabilized gasoline fraction represented about 49.1 per cent by weight of the charge to the case and the cycle stock about 42.7 per cent of the charge to the case. (Both values on a weight basis.) The untreated gas oil fraction on cracking yields about 43.7 per cent by weight of unstabilized gasoline and about 46.4 per cent by weight of cycle stock. In the cracking of the alkylated gas oil about 2.8 per cent of coke was produced whereas the cracking of the untreated gas oilresulted in the production of 3.7 per cent coke. The over-all yield of stabilized gasoline with end point of 410 F. from the cracking of the alkylated gas 011 stock was about 42.3 per cent by weight based upon the amount of gas oil treated. The over-all yield of unstabilized gasoline amounted to 48.2 per cent by weight based upon the amount of gas oil treated.

The following 'data are illustrative of the advantages derived from applying the principles of the present invention:

. Original Properties or buizl ag hm is. end 'gf flfiwgg u ge t d aso e ed Raiflnate Fraction A. P. I. gravity 54.0 52.1 Bromine number 0. 9 l5. 4 Aromatics .volume per cent... 26. 8 2S. 4 Total Sulfur .weight per cent. 0. 07 0. l7 Mercaptan Sulfur .do- 0. 015 0. 0516 Yield of asoline do 42. 3 30. 2 Unstabii zed gasoline to coke ratio. 17.521 ll.8:l

Those skilled in the art will appreciate what the I forming said mixture into a hydrocarbon layer and a liquid hydrogen fluorideflayers separating said hydrocarbon layer from said liquid'hydrogen fluoride, and subjecting aid hydrocarbon layer to cracking.

3. A process for producing relatively low sulfur gasoline while increasing the gasoline to coke foregoing results mean to the art. The increase in the gasoline to coke ratio indicates the marked improvement in the operation of the cracking unit attainable by use of this method of treating materials such as' gas oils. As a result of the reduced amount of coke produced in cracking regeneration of the catalyst will be necessary only ratio which comprises mixing a hydrocarbon fraction containing at least about 0.5 per cent sulfur and at least about 20 per cent alkylatable constituents, a hydrocarbon fraction containing at least about per cent alkyiating constituents and suflicieht hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride for at least about 10 minutes to form a mixture. at least one of said hydrocarbon fractions having a boiling range at least that of gas oil forming said mixture into at least a hydrocarbon layer and a liquid hydrogen fluoride layer under conditions of temperature and pressure at which said hydrogen fluoride is I liquid, separating said hydrocarbon layer, conat greater intervals during operation or the time of regeneration will be less when the on stream" period is the same.

While the present invention has been described in conjunction with certain preferred embodiments thereof it is to be understood that the examples provided hereinbefore are illustrative but not limiting. Furthermore, the term relatively high sulfur content is to be interpreted as including suitable materials containing more than about 0.1 per cent sulfur whereas the term relatively low sulfur content" has been used to designate materials containing up to about 0.1 per cent sulfur.

In addition, as those skilled in the art know, the term space velocity is defined as the volume of oil passing through a given volume of catalyst per hour.

We claim:

tacting aid hydrocarbon layer with an aluminaditions such that said hydrogen fluoride is liquid,

1. A process for producing gasoline having a relatively low sulfur content from petroleum fractions having a relatively high sulfur content which comprises mixing a first petroleum fraction containing alkylatable constituents and having a sulfur content of about 1.50 per cent with a second petroleum fraction containing about 64 per cent oleflns and having a sulfur content of about 0.76 per cent in the proportion of about 436 parts by weight of the first fraction to about 152 parts by weight of the second fraction to form a treating stock, the boiling range of at least one of said fractions being mainly above 400 F., agitating said treating stock with about 105 parts by weight liquid hydrogen fluoride at about C. to about C. for about 20 to about 30 minutes at a pressure such that a substantial portion of the hydrogen fluoride remains liquid to-obtain a rafflnate, separating said raflinate from liquid hydrogen fluoride, cracking said raflinate, and recovering a fraction boiling within the motor fuel range.

2. A process for producing relatively low sulfur gasoline while increasing the gasoline to coke ratio which comprises mixing a hydrocarbon fraction containing about 34 per cent aromatics, about 1.57 per cent sulfur, and having an initial boiling point of about 360 F., a hydrocarbon fraction containing about 64 volume per cent oleflns and suflicient hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride, to form a mixture, agitating said mixture for at least 10 minutes under conditions of temperature and pressure with which hydrogen fluoride is liquid,

separating said hydrocarbon oil from said liquid hydrogen fluoride, and cracking said hydrocar; bon oil.

5. A process for increasing the gasoline to coke ratio while reducing the sulfur content of the gasoline produced by cracking petroleum fractions having a relatively high sulfur content which comprises mixing an alkylatable fraction of petroleum oil having a relatively high sulfur content with a petroleum fraction having an olefin content in excess of about 5 per cent, one of said fractions having a boiling range not lower conditions of temperature and pressure such that i said hydrogen fluoride is in the liquid state, separating a hydrocarbon layer from a liquid hydrogen fluoride layer, subjecting said hydrocarbon layer to cracking conditions and recovering gasoline from said cracking operation.

6. A process for producing low sulfur gasoline while increasing the gasoline to coke ratio which comprises treating an alkylatable fraction of petroleum oil having a relatively high sulfur content and boiling above 400 F. and a relatively low boiling point fraction of petroleum containing an appreciable quantity of oleflnic material with sufficient hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride, stratifying the aforesaid materials into a hydrocarbon layer and a liquid hydrogen fluoride layer, separating said hydrocarbon layer from said liquid hydrogen fluoride layer, cracking said hydrocarbon layer and recovering. a fraction boiling within the motor fuel range and having a relatively low sulfur content.

7. In t-h process for producing gasoline by cracking of petroleum containing an appreciable proportion of constituents boiling above about 400 F. and separating a fraction boiling within the motor fuel range, the improvement which comprises treating the stock to be cracked and containing not less than about 0.5 per cent sulfur, alkylatable and alkylating constituents with suflicient hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride to obtain treated stock, separating treated stock from liquid hydrogen fluoride and cracking said treated stock.

8. In the process for producing gasoline by cracking a relatively high sulfur stock containing alkalatable constituents and separating a fraction boiling within the motor fuel range the improvement which comprises admixing hydrocarbon material containing alkylating constituants and having a relatively high sulfur content with hydrocarbons containing alkylatable constituents to form a cracking stock, at least one component of said cracking stock having a boiling range about 400 F. treating said cracking stock 8' ditlons or temperature and pressure that the hydrogen fluoride is liquid, separating a liquid hydrogen fluoride portion from a liquid hydrocarbon with suflicient liquid hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride to obtain treated desulfurized stock and cracking said treated stock.

9. In the process for-producing gasoline by cracking petroleum stock boiling above 400 F. containing alkylatable constituents and separating a fraction boiling within the motor fuel range, the improvement which comprises admixing hydrocarbon material containing alkylating constituents with said petroleumstock to form a cracking stock, treating said cracking stock with suflicient liquid hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride to obtain treated stock and cracking said treated stock.

10. A process for producing gasoline from petroleum fractions which comprises mixing a cracking stock fraction boiling mainly above 400 F. with a liquid fraction of lower boiling range to provide a mixture containing up to about 20 per cent by volume alkylating substances and alkylatable material in amount sumcient to alkylate with substantially all of said alkylating substances, agitating said mixture with sufflcient liquid hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride under such conportion, and subjecting said hydrocarbon portion to cracking.

11. A process for producing low sulfur gasoline while increasing the gasoline to coke ratio which comprises treating a gas oil containing alkylating constituents and having a relatively high sulfur content and naphtha containing alkylatable constituents with suflicient hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride, separating aliquid hydrogen fluoride portion from a liquid hydrocarbon portion, and cracking said hydrocarbon portion.

12. A process for producing low sulfur gasoline while increasing the gasoline to coke ratio whichcomprises agitating a fraction of petroleum oil boiling mainly above 400 F. and containing an appreciable amount of alkylating material and a relatively low boiling point fraction of petroleum containing alkylatable constituents and having a relatively high sulfur content with sumcient hydrogen fluoride to ensure liquid phase separation of hydrogen fluoride, separating a liquid hydrogen fluoride portion from a liquid hydrocarbon portion, and subjecting said hydrocarbon portion to cracking conditions.

JACOB R. MEADOW.

WILLIAM A. STOVER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,322,800 Frey June 23, 1943 2,267,730 Grosse et al Dec. 30, 1941 2,260,944 Goldsby et a1 Oct. 28, 1941 2,337,640 Burgin Dec. 28, 1943 2,310,327 Sweeney Feb. 9, 1943 2,352,236 Thomas June 27, 1944 2,203,470 Pier et al June 4, 1940 2,395,198 Schulze Feb. 19, 1946 2,382,505 Schulze Aug..14, 1945 2,378,762 Frey June 19, 1945 FOREIGN PATENTS Number Country Date 292,932 Great Britain May 23, 1929 

